An actuator is a device that converts one form of energy into some type of motion. There are several different types of actuators, including pneumatic, hydraulic, electrical, mechanical, and electromagnetic. An electromagnetic actuator provides mechanical motion in response to an electrical stimulus. The electromagnetic actuator typically includes a coil and a movable armature made of a ferromagnetic material. A magnetic field is produced around the coil when current flows through the coil. The magnetic field applies a force to the armature to move the armature in the direction of the magnetic field.
Some electromagnetic actuators are limited in the type of force that can be applied to an armature. For example, an armature can be pushed but not pulled. Additionally, some electromagnetic actuators may produce a negligible amount of force when a small amount of current is applied to the coil. And in some devices or components, such as in portable electronic devices or components used in portable electronic devices, it can be challenging to construct an electromagnetic actuator that has both a reduced size and an ability to generate a desired amount of force.